WINE-OCHRA RISK Informe resumido

DNA-based characterisation of A. carbonarius

In order to characterize by molecular methods responsible species involved in the ochratoxin A (OTA) contamination of grapes from Europe and Israel, a total of 189 strains of black aspergilli, including A. carbonarius and uniseriate species (A. aculeatus, A. japonicus), were studied. Sixty six strains were morphologically identified as belonging to the uniseriate species and 123 as A. carbonarius. None of the uniseriate species were able to produce OTA. From the A. carbonarius strains, 96.7% were OTA producers (0.1 to 654.3 mg/g). We characterized 53 strains of A. carbonarius from different countries by RAPD and ITS-5.8S rDNA sequencing analysis. Forty nine strains have a similar RAPD pattern and identical ITS-5.8S rDNA sequences. They produce OTA at different levels. No correlation was determined between the obtained clusters and OTA production level or origin. Only four strains, morphologically identified as A. carbonarius, were not able to produce OTA. These strains showed a different RAPD pattern and the section of DNA sequenced differed from the sequence of the other 49 strains. These OTA-non producing strains represent a new species in the Aspergillus section Nigri. This study also confirms the high percentage of OTA-producing strains in A. carbonarius and the inability of the uniseriate black Aspergillus species to produce OTA.